In a traditional technology, a light guide plate (LGP) in a side-light type LED (light emitting diode) backlight module is generally rectangular. FIG. 1A and FIG. 1B are schematic views of a structure of a side-light type LED backlight module in a traditional technology, wherein FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view of FIG. 1A taken along a line A-A. The backlight module comprises a back plate 11, two aluminum extrusion members 12, two driver circuit boards 13, a plurality of LEDs 14 and a light guide plate 15. The light guide plate 15 is disposed on a central portion of the back plate 11, and is a rectangular structure. The driver circuit board 13 is provided with the plurality of LEDs 14, and commonly mounted on two sides of the light guide plate 15 with the LEDs 14. The LEDs 14 generate light which is emitted into the light guide plate 15, and then scattered to form uniform light used as a backlight source of a liquid crystal display (LCD). The aluminum extrusion member 12 is mounted between the driver circuit board 13 and the back plate 11 which is used to dissipate heat generated during the LEDs work into the ambient environment by the high thermal conductivity of aluminum material. In a large-size side-light type LED backlight module, the LEDs 14 generate and accumulate heat, so that it needs to use the aluminum extrusion member 12 to guide the heat toward the bottom of the back plate 11 for dissipating the heat outward. Because the volume of the light guide plate 15 and the aluminum extrusion member 12 is considerably large, the backlight module of an LED backlight type display is relatively heavy. Because it inevitably needs to transmit the heat to the back plate 11 through the aluminum extrusion member 12, an area disposed with the aluminum extrusion member 12 will accumulate the heat, and thus the brightness and color generated by the light guide plate 15 may be uneven.
If wanting to reduce the weight, the backlight of the LED backlight type display generally must use the direct-light type design, i.e. the LEDs must be mounted on the bottom of the back plate in the backlight module. However, it needs a longer light mixing distance, so that the direct-light type LED backlight module needs a greater thickness.
As described above, the backlight design of the LED backlight modules in the traditional technology can not meet needs of light weight and compactness at the same time.